The families have sued the manufacturer, Airbus Helicopters, saying the copter had a malfunction in its tail rotor.

The NTSB believes the pedals were misconfigured before the accident and the copter did not have an alert to let pilots know about the problem.

They also say the pilot did not perform a hover check, which would have let him know about the problems in controlling the helicopter.

Statement From The National Transportation Safety Board

“The National Transportation Safety Board (NTSB) is providing the following information to urge the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) to take action on the safety recommendations in this report. These recommendations address the need for owners and operators of existing AS350 B3e helicopters and similarly designed variants to incorporate a crash-resistant fuel system into their rotorcraft. These recommendations are derived from two 2015 accidents in which the impact forces were survivable for occupants but fatal and serious injuries occurred because of post crash fires that resulted from an impact-related breach in the fuel tanks. As a result of these investigations, the NTSB is issuing three safety recommendations tithe FAA and one safety recommendation to EASA.”